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Finding the best step size
Posted May 2, 2014, 5:35 a.m. EDT Results & Visualization, Studies & Solvers 0 Replies
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I've been trying to simulate flow past a (hot) cylinder. I simulate Re-Numbers up to 190.
After running the simulation for various step sizes (0.5/1/10/20/50/100 s) I tried to visualize the relative errors of some specific values with respect to the value acquired with step size 0.5s.
The errors cocnerning temperature and v_max are insignificant - or at least not too bad (max is about 15%), but the errors concerning the velocity at some points are much worse (max is 95%).
I noticed different things: The errors for step sizes from 10s to 100s are almost the same, no big difference and the errors for step size 1s is sometimes even bigger than the ones for higher step sizes. Is it possible, that the step size 0.5s is too small? And is there a minimum step size?
The simulation time is 12400s and the water tube is about 1.20m in length. It may also be a problem that the vortexes that occur behind the cylinder develop at different times by using different step sizes and that I just cannot evaluate the same points at the same simulation times. But if that's the case, wouldn't the errors for the step sizes 10s to 100s be very different, too?
Best regards
Alexander Spranger
Hello Alexander Spranger
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